Of P-51s and Yaks

Those Sterling profile kts of the '50s were excellent flyers. Buy a kit on Thursday and fly it on Sunday. I built several of each type, but I think the Yak was the better flyer. I opted for installing flaps, but I wonder if anyone built them with the flaps glued in place (quicker to build). Any comparison would be appreciated.
Floyd in OR

I built a P-51 and a YAK with flaps. I also have a P-51 built by another guy without flaps. The flapped Mustang does turn tighter and smoother, but it's also 6 oz lighter. So, maybe it's not a fair test.
Both were powered with older Fox .25's turning 9-5 props.

I had both the Yak and the P51 built them both with flaps but I also built a second Yak without flaps. I honestly couldn't tell any differance, which at the time kind of bothered me. In fairness I was not doing alot of tight corner stuff, so maybe that's why.
Andy

The biggest problem I found with installing flaps on the Yak-9 was the that the trailing edge is angled.The flaps bind as they sweep upwards and vice-versa.I did make it work with cloth hinges though.They were very sloppy but they did little for the performance.My fixed flap version does real well.I currently fly 3 of them.They aren't the most spectacular flying but they taught me how to fly inverted.I guess you never forget your first plane. Ken

I have two Yaks right now, and had a P-51. All three were swap meet restorations that I did. Both Yaks had excessive gaps with the flaps, so I need to reserve judgement, but all three only flew fairly well (Mustang had no flaps). The Yaks were drilled out for Foxes, and the P-51 for Enyas (29 and 35). Even with the Fox light wt, they are way overpowered. A better choice is the OS 20 FP or even a decent ABC 15, again the FP would work well.

Looking at the short coupling, I doubt if flaps really make much of a difference.

Both present well in the air, especially with colorful paint jobs. I camouflaged one Yak so well, that people were almost stepping on it.

The larger Sterling profiles are better fliers, such as the Ringmaster, F-94, later F6F Hellcat, Navion, etc.

Currell

Oh, my! Now you're taking me down Memory Lane. Had my first ones when they hit the market in the early '50s ($2.95 a pop). First thing that came to mind when I saw the title of this thread was the delicious aroma of Testors STA...Fox 29s...Powermist fuel and 10-6 Top Flites. Not exactly what you'd call Precision Aerobatics, but those old profiles sure were fun.

Build several since then, both the Yak and Mustang, all with movable flaps. The most recent was the Yak built after returning from Free Flight in 1987: completely Monokoted (big mistake!) and minus landing gear. Hand-launched, it was actually built to compete in Balloon Bust at Whittier Narrows. With an OS .35FP it was a very nice flyer until I re-covered it, added undercarriage and entered it in Classic at VSC-III --- about which the less said, the better.

There must be something said for stationary "flaps" on the Mustang, though, since Lou Wolgast won Nats OTS several times with one.

Mike Keville

I always liked the yak best...they both flew better than ringmasters...and firecats weren't even in the running (not meaning to hijack ur post)....jim

I built several of each in the 50's and all had moving flaps. I thought the Mustang flew better.In the 1980's I built a light Mustang with fixed flaps for old time use. I felt it didn't turn as well as I remembered the old ones turning.I cut the flaps loose and hinged them using 2/3 to 1 and it turned much better.Most of the older ones I built had the gear in the wing.
Ed

You get a lot of different responses on the fixed verses moveable flaps on the Mustang/Yak. I built two of each and still have the two Mustangs. I built the first Mustang. Beautiful flyer. Super tight turning corners. I built the second exactly like it (I thought) and it didn't turn well at all. After much fussing with it, I discovered that when I held the flaps the pushrod from the belcrank to the flaps would bend and do funny things. I cut into it and put in a good system and bingo!

I think this is the biggest reason why some who used moveable flaps say they didn't work on this plane. Their controls were sloppy because that is the way the kit is designed. If you build it with moveable flaps and a bullet-proof control system, you should be well pleased with it.

(Oh, and I didn't know any difference in performance between the Mustang and the Yak. Again, it might be the way the controls were set up.)

You know Len you might be exactly right on the control problems. I always built them with the stock control system. If I were to build one today it would be much different. By the way Len do you have the plans for the Mustang or the Yak?
Andy

>You know Len you might be exactly right on the control
>problems. I always built them with the stock control system.
>If I were to build one today it would be much different. By
>the way Len do you have the plans for the Mustang or the Yak?
>Andy

I have the plans for the Mustang. I also have lazer cut rib sets for it for those who might want to build it. I just never got around to advertising these yet.

Len
I already ordered a set of plans from Bare, but I would like a set of ribs for both the Yak and the P-51. Let me know what the cost is and I will put a check in the mail. Send me an email and we can do business please.
Andy

Responses so far are just about what I expected: some say the Yak is better, and others say the P-51 is better!! Could be variations in kit balsa (weight) and/or engines used? All mine were powered by the Fox 35. Way too much HP, but I bought motors at the Army base PX for $10, back in 1952. So for about $15 you could start from nothing and have a pretty decent plane to crunch on the weekend! At that price we could afford to crash them regularly and not feel so bad about it.

As for flaps not being very helpful on a short-coupled plane---I'm reminded of the Veco CHIEF--short tail moment with flaps -which is still a great performer.

Floyd

For those of you who think the Fox 35 over powers these things, Dad's were powered by a McCoy 35 or a K&B Greenhead 35. Just to let you know.

Here they are.



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I've got a Yak. It came with flimsy, loose moving flaps. I rebuilt the plane with the flaps stationary.

No need for flaps on such a small plane, too much weight and mechanics on little airplane. The major-league bent TE is the clincker.

Is anyone puttin' out a kit of either one of these excellent old Gal's ? Sure would be nice to build one... Ah, the nostalgia...And the old times too.... [photo not recovered: sipcof.gif]

Barry Baxter has full-sized plans for both. www.controllineplans.com

Mike Keville

> Is anyone puttin' out a kit of either one of these excellent
>old Gal's ? Sure would be nice to build one... Ah, the
>nostalgia...And the old times too.... [photo not recovered: sipcof.gif]

I don't have a kit, but I do have lazer cut rib sets and full size plans for the Mustang.

I think brodaks may be coming out with these two in kit form pretty soon - I saw a photo of the Yak on this or the other forums and it was in development for a new kit.

Lets hope.....

>For those of you who think the Fox 35 over powers these
>things, Dad's were powered by a McCoy 35 or a K&B
>Greenhead 35. Just to let you know.
>
>Here they are.
>
>
>
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>

You have to remember, these planes are old. They were both bult in the mid 50's. The white one has had the rudder knocked off and it has been recovered when we cut into it and replaced the control system. Just a basic paint job to see how it flew. It flew fine. Never bothered after that to make it prettier.

I built about 8 of the Sterling P51\Yak planes in my youth. Two Mustangs and 6 Yaks. All of them were built with flaps and on ALL of the Yaks, I used straight trailing edges.

The Yak outflew the Mustang hands down hence the difference in numbers built. IMHO, the straight trailing edge-flapped Yak beat the Ringmaster and a lot of other profiles of that time going away.

The Magician was good, no doubt about; but the straight trailing Yak with flaps became the "go to plane" for me. It is really the Yak series of planes that I got my "thing together" when I was young,(no jokes, yes I was young once).

My first "big" plane was the Sterling Mustang with flaps and a Fox 35. Still have the Fox. I painted mine with Aerogloss metallic blue with white canopy, and white invasion stripes. I used the star decals that came in the kit, and it flew very well. I burned lots of Superfuel in that plane.

WOW! these were both good planes that I learned to fly on with the 35 size motors. First one was the Mustang that I flew in early 60's with the Red Head Fox Rocket, destroyed it learning to invert. Built a second one in late 60's along with the neat Yak 9. All had working flaps but don't recall the issues with the controls as Lenoard states. The latter Mustang and Yak, both flew with K&B green head 35's. I felt that they were a little over powered with these motors, even dropped to a 10x4 prop. The mustang would turn real tight, even to the point of lugging the motor down. I crashed the second Mustang just this past summer while doing overhead 8's, starving it for fuel. Painted the Mustang per instructions, yellow and silver, while the Yak was gray. Too bad these are not kitted today as it sounds like they still have a following. I Thank You.

>WOW! these were both good planes that I learned to fly on
>with the 35 size motors. First one was the Mustang that I flew
>in early 60's with the Red Head Fox Rocket, destroyed it
>learning to invert. Built a second one in late 60's along with
>the neat Yak 9. All had working flaps but don't recall the
>issues with the controls as Lenoard states. The latter Mustang
>and Yak, both flew with K&B green head 35's. I felt that
>they were a little over powered with these motors, even
>dropped to a 10x4 prop. The mustang would turn real tight,
>even to the point of lugging the motor down. I crashed the
>second Mustang just this past summer while doing overhead 8's,
>starving it for fuel. Painted the Mustang per instructions,
>yellow and silver, while the Yak was gray. Too bad these are
>not kitted today as it sounds like they still have a
>following. I Thank You.


If Brodak's catalogue is correct they will be available in the future. John Brodak bought Walter Umlands past kit line which included these 2 planes.
dennis

Dennis is correct.

Brodak will be offering kits of both. I've seen the prototypes and they are very well done.

Regarding kit price and availability, that should be available from Brodak.

Bob Z.

I have a Yak about 75% finished. I am building it for OTS so I did not use the flap option. It will be powered by an old Veco 19BB which is in great shape. The finish will be OD over Lt. Blue with markings from a Russian Squadron I found a picture of.

I don't do a LOT of OTS flying, but I enjoy it, and 10 points will always help (no flaps).

Big Bear <><
Character: It's what you do when no one else is watching.

All too often, we attribute a model's relative flying abilities to differences in design. The Mustang and Yak are pretty close in span, area, moments, etc, so I don't think basic design distinctions are the answer. One of the two probably has a slight inherent advantage purely to design, but I don't know which one to put my $ on.

It probably comes down to trim differences, weight differences, the engine run you got, which way the wind was blowing, etc, way back in '55 on that fine Summer day you flew both models, or saw both models fly. You formed your Yak vs P-51 opinion. And unswervingly have held it since...And I am as guilty of this as anyone...

Currell

OK, so I hyjacked the thread !!

Another plane of that era that beat 'em both was the Galaxy. The kits were a low-grade disaster, but now there are plans and (I tink) Brodak kits available.

Here's Big Art's Galaxy.

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This setup really sold me on Greenheads with tongues.


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This tread has spurred me to order a set of plans for both the Yak and the P-51 from Bare. I had fun with both thoughs planes and I have plenty of engines from that era just waiting for planes.

I actually went to Google Earth and looked in on Korat Royal Thai Airbase where I was station in 1967-68 and think I located the field where we flew control line. That was where I had my second Yak. Covered with parachute fabric and doped with paint used on the EC-127's. One time we ran out of fuel, a few of us went into town and visited every pharmacy in town buying all the methanol alchol and castor oil they had. We had fuel to fly on until a shipment of real fuel came in from Japan. You do what you have to do!
Andy

Floyd,

Put me in the YAK-9 column.

Built two from Sterling kits in the 1980's. One built light with kit wood (!), and the other took some serious lightening, mostly in the LE, to get to the same weight: ~30 oz. Fox 35's on both.

Colors and markings from an old red/white Profile Pub monograph, may have done wing gear on at least one of them.

Flapped. Linkage was a nuisance - a Rube Goldberg setup using a cross shaft thru the fuse and those early, itty-bitty snap-together ball links. Worked solid, free and smooth from the leadouts, but for some reason was about irreversible from the flaps and elevators.

Excellent fliers, both.

I think the YAK flaps are a bit broader chord than on the P51, and those rounded tips may add another 30-40 sq in of area. Couldn't hoit, no?

IMHO, a light, straight Ringmaster does fly better than either "warbird." Thrust line, chord lines are more nearly in line. The warbird fuselages are pretty tall. But the Korean War-inspired, natural-enemy warbird duo were both very nice, and easier on the eyes from the handle.

The P51 & Yak both where good flyers but the midwest P51 looked better in the air.

Mike Clark

>Buy a kit on Thursday and fly it on Sunday.

Now that probably explains how I managed to build and fly my Yak in one summer!

I built a Yak-9, my first "big" madel, around 1958, while in Jr. High School. I used the flaps and just followed the instructions, as my only knowledge of how to build such a model. I lucked out. Weight must have been acceptable, despite lack of sand paper, and there were no wrinkles. Mine flew better than a friend's P-51 and much better than the neighborhood Ringmasters that wallowed around the hemisphere, probably due to excessive out thrust, rudder, and white-knuckle piloting techniques. Since I flew that way too, I think that means the Yak was less affected by being yanked around.

I had no knowledge of the pattern and just copied what I saw: wingovers, round loops, horizontal lazy-8's, and what I thought was a vertical-8, the outside loop being at the bottom. All these were done in a maximum of 60-70 degrees vertically. So, despite meeting its demise (twice - had a 'second coming') in such a vertical-8, it was actually able to do this.

I flew it with a $5.98 special McCoy .35 in a brisk 2-cycle on 52-foot lines. I loved that plane.

Hence the silvered, world's heaviest Yak her behind me, begun in 1960 and "completed" in 2002.

Edit: There have been a couple around here with the control horn bent shallower in two places, with the trailing edge sanded laterally at the joint. This together with whatever hinges they used (one used pinned hinges) allowed the flaps to drop of their own weight in apparent defiance of mechanical principles, like Bill Werwage's "Ares" flaps. Mine were built per plans and kit-supplied 1/8" wire flap connectors. They do resist deflection, having a self centering tendency from required twisting of the flaps.

SK

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Looks just like my Sterling Mustang! (the paint) For me, it was 1955, just crashed my Ringmaster, so Sterling Mustang was next. Fox .35, with flaps. Was still flying it when I got the Yak. Same stock buildup, w/ flaps, Fox .35. Yak was more responsive, due to my lame over-control that years have finally helped. Yak dropped like a brick when the fire went out, Mustang glided 3/4 of the lap!
Yaks have been popular at my house, have been converted to Mystery ships, T-6, P-40, P-26a, and Seversky P-35. (subtle liberties taken with flap & tip shape)
Seriously, of all the profiles, these are still favorites of mine, and following Ringmasters, these were the Hot Rods.
Thanks to Ty, I have another P51 "in the wings". Glad to hear Len has ribs & plans. There will be more...

I'm also in the Yak-9 fan club. First "Big plane" that I flew inverted. Flew great with a weak Fox.35 (it sucked a lot of sand on the baseball fields we flew on).Aero Gloss curtis blue fuse.& rudder,swift white wing & stab,2" K&B raceing wheels. I scored a lightly built one from the "Mummys' Toumb" at a swap meet.Needs a lot of restoration but it'll be worth it.

I still have a P-51 I built in 1964 I fly on a regular basis powered with a Fox 35. Flys great but is getting a little loose. My Yak-9 I started about the same time and tabled it and finished it in the late 80's and is powered by an old 4 bolt head Veco 35 and also flies great. Love these old planes and old engines. I've got lots of them and I love flying them all.

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